For the past few years, grid giants including Siemens, GE, Alstom, Toshiba and Schneider Electric have been working on demand response management systems -- technology platforms to integrate smart grid technologies with energy assets on the customer side of the meter. In general, they’ve taken grid-focused, utility-centric approaches to this challenge, as befits their roles as suppliers to the utility industry.

But there’s another side of the demand response industry, led by big aggregators like EnerNOC, Comverge, Constellation Energy and NRG Energy, which go out and secure megawatts of demand reduction capacity from thousands of customers. It’s a more customer-centric model, and it requires technology to merge grid control and energy market transactions across a variety of utility or grid operator jurisdictions.

This week, Siemens announced a partnership with U.S. retail energy services provider Direct Energy that takes the company's DRMS software into this demand response aggregation realm for the first time. It’s the biggest deployment yet for Siemens’ demand response technology, and it’s also the first being put to use by a utility without direct control over the wires that carry electricity to the customer.

Direct Energy, a subsidiary of U.K. energy company Centrica, has about 6 million residential and commercial customers in the United States, and is already working with partners like Honeywell and Opower on residential demand response.

But Direct Energy’s work with Siemens will focus on the commercial and industrial demand response customers it got when it acquired Hess Energy last year. That brought it 23,600 customers in territories served by grid operators including PJM, ISO-NE, ERCOT and NYISO, putting it into the top ranks of demand response aggregators -- much like Constellation Energy did when it bought CPower in 2011, or NRG Energy did with last year’s purchase of Energy Curtailment Specialists.

Siemens has previously deployed its DRMS with small utilities in the U.S. and Canada, and is also working with larger investor-owned utilities and grid operators, said Sachin Gupta, demand response product manager for Siemens Smart Grid, in an interview.

But working with Direct Energy required some new approaches to some core challenges, like getting the verifiable, “revenue-grade” energy metering data from each building in the system.

“Because they’re a retail electric provider, they don’t necessarily have access to the meter like a traditional utility would,” he said. “But they’ve already deployed submeters out on each one of their consumer accounts, and part of our plan is to go and integrate to those submeters -- one, to show them near-real-time data during an actual DR event, and two, to provide them with automated measurements and verification capability, billing and settlement data, and store that consumption data within the same data warehouse.”

Siemens is applying the software smarts of eMeter, the meter data management system company it bought in 2012 and has integrated into its DRMS software suite, to help in this submeter measurement and verification (M&V) work, Gupta said.

It’s also providing analysis and forecasting to tighten the certainty Direct Energy has in how much energy each building will be able to reduce in days, weeks or months ahead of time. Omnetric Group, the joint venture formed between Siemens and Accenture last year, is supporting the grid-operator-to-individual-load software integration.

This kind of portfolio-wide energy data analysis and optimization is part of what DR aggregators like EnerNOC are offering their clients as well. Right now, the main benefits come from better matching the energy-reducing capabilities of potential and existing customers with the emergency, economic and grid services programs and markets now open to them.

In the future, companies like Direct Energy with a stake in energy markets could use demand reduction assets as a hedge in their electricity purchase and delivery contracts, he added. That’s also been a stated part of the demand response plan for Constellation Energy, at least before it was purchased by Exelon, and it’s easy to imagine NRG Energy and others looking to demand management as part of their asset mix.

“I think most entities headed down this path are fairly tight-lipped about what their strategies are,” including Direct Energy, when it comes to using demand-side resources in energy markets, Gupta said.

Direct Energy is planning to use Siemens’ DRMS to expand the range of services it provides across the country, including more fast-reacting demand response for grid services like frequency regulation, which Siemens is now testing with Canadian utility New Brunswick Power, he noted.

Direct Energy, like its retail energy brethren, is busy expanding the range of services it provides customers to integrate new technologies like remote-control hot water heaters, rooftop solar and home energy management systems. On that front, the work Siemens has been doing on “surgical” demand response -- turning down power to help local distribution grid problems as well as system-wide markets -- could find uses as well.